We present results on time-resolved transillumination imaging by using the cumulant expansion solution to the transport equation for temporal extrapolation. The resolution study involves measuring the edge response function (ERF) for a mask embedded in a liquid phantom at near-IR wavelengths, obtaining the integration-time-dependent resolution for different phantom widths and verifying this spatial resolution by resolving two objects inside the phantom. We also present results on the values of different parameters of the phantom materials and the feasibility of this method to characterize the absorption and scattering coefficients of a turbid medium.
We present results of resolution and optical characterization studies of silicon dioxide nanoparticle solutions. These
phantoms consist of spherical particles with a mean controlled diameter of 168 and 429 nm. The importance of this work
lies in using these solutions to develop phantoms with optical properties that closely match those of human breast tissue
at near-IR wavelengths, and also to compare different resolution criteria for imaging studies at these wavelengths.
Characterization involves illuminating the solution with a laser beam transmitted through a recipient of known width
containing the solution. Resulting intensity profiles from the light spot are measured as function of the detector position.
Measured intensity profiles were fitted to the calculated profiles obtained from diffusion theory, using the method of
images. Fitting results give us the absorption and transport scattering coefficients. These coefficients can be modified by
changing the particle concentration of the solution. We found that these coefficients are the same order of magnitude as
those of human tissue reported in published studies. The resolution study involves measuring the edge response function
(ERF) for a mask embedded on the nanoparticle solutions and fitting it to the calculated ERF, obtaining the resolution
for the Hebden, Sparrow and Bentzen criteria.